Process for the preparation of 1-phenylindan photoinitiators

ABSTRACT

The invention relates to a process for the preparation of a crystalline isomeric mixture of compounds of formulae (I) and (II) which process comprises the following steps: a) the slow addition of aluminium chloride, in portions, to a solution comprising 1,1,3-trimethyl-3-phenylindan and isobutyric acid halide in a suitable solvent at a reaction temperature of from −20° C. to 20° C., an isomeric mixture consisting of compounds of formulae (Ia) and (IIa) being obtained; b) enol chlorination of compounds (Ia) and (IIa), an isomeric mixture consisting of compounds of formulae (Ib) and (IIb) being obtained; c) hydrolysis of the chlorinated isomeric mixture from step b). The invention relates also to the preparation of the individual compounds (I) and (II).

The invention relates to a novel process for the preparation of1-phenylindan photoinitiators, especially of2-hydroxy-1-(3-[4-(2-hydroxy-2-methyl-propionyl)-phenyl]-1,1,3-trimethyl-indan-5-yl)-2-methyl-propan-1-oneand2-hydroxy-1-{1-[4-(2-hydroxy-2-methyl-propionyl)-phenyl]-1,3,3-trimethyl-indan-5-yl}-2-methyl-propan-1-one.

U.S. Pat. No. 4,987,159 describes a process for the preparation of theabove-mentioned mixture by Friedel-Crafts acylation of1,1,3-trimethyl-3-phenylindan using isobutyric acid chloride inmethylene chloride. The corresponding bis-isopropyl ketone is formed andis chlorinated using sulfuryl chloride. Subsequent hydrolysis withsodium methanolate and then with dilute hydrochloric acid yields amixture of2-hydroxy-1-(3-[4-(2-hydroxy-2-methyl-propionyl)-phenyl]-1,1,3-trimethyl-indan-5-yl)-2-methyl-propan-1-oneand2-hydroxy-1-(1-[4-(2-hydroxy-2-methyl-propionyl)phenyl]-1,3,3-trimethyl-indan-5-yl)-2-methyl-propan-1-one.The product is wax-like and tacky and contains small amounts ofoligomeric compounds, which inhibit successful crystallisation.Purification of the tacky product can be carried out by means of columnchromatography.

WO 02/0855832 describes the above-mentioned mixture of2-hydroxy-1-(3-[4-(2-hydroxy-2-methyl-propionyl-phenyl]-1,1,3-trimethyl-indan-5-yl)-2-methyl-propan-1-oneand2-hydroxy-1-(1-[4-(2-hydroxy-2-methyl-propionyl)-phenyl]-1,3,3-trimethyl-indan-5-yl)-2-methyl-propan-1-oneas a constituent of a solid mixture of alpha-hydroxycarbonyl derivativesof alpha-methyl-styrene oligomers.

The object of the present invention was to provide a pulverulentcrystalline product largely devoid of oligomeric constituents.

The object was achieved by the process described hereinbelow.

Process for the preparation of a crystalline isomeric mixture ofcompounds of formulae I and II

which process comprises the following steps:

-   -   a) the slow addition of aluminium chloride, in portions, to a        solution comprising 1,1,3-trimethyl-3-phenylindan and isobutyric        acid halide in a suitable solvent at a reaction temperature of        from −20° C. to 20° C., an isomeric mixture consisting of        compounds of formulae Ia and IIa being obtained    -   b) enol chlorination of compounds Ia and IIa, an isomeric        mixture consisting of compounds of formulae Ib and IIb being        obtained    -   c) hydrolysis of the chlorinated isomeric mixture from step b).

The following reaction scheme gives an overview of the reaction steps.

Important factors in reaction step a) are the use of pure1,1,3-trimethyl-3-phenylindan having a low oligomer content, the choiceof solvent, the slow metered addition of aluminium chloride and themaintenance of a temperature below 20° C. Above 20° C., the isobutyricacid chloride slowly decomposes with the liberation of CO and yieldsadditional isopropyl derivatives in the Friedel-Crafts reaction.

Any solvents that are inert under the given reaction conditions arepossible, for example ethylene chloride, trichoroethylene, methylenechloride, tetrachloroethane, chlorobenzene, bromobenzene,dichlorobenzene, cydohexane, methylcydohexane, carbon disulfide,nitromethane, nitroethane, nitropropane and nitrobenzene. Chlorobenzeneor 1,2-dichlorobenzene is preferred.

A solvent that is especially preferred is 1,2-dichlorobenzene. Althoughmethylene chloride is possible in this reaction, it is less suitablebecause it participates in the reaction to a small extent, leading tothe formation of oligomeric compounds which interfere with thecrystallisation process.

The metered addition of aluminium chloride must be carried out slowly,for example over a period of from 2 to 3 hours. It is important to avoida local overdosing of aluminium chloride, because a high aluminiumchloride concentration causes the starting material1,1,3-trimethyl-3-phenylindan to isomerise, which likewise leads to theformation of oligomeric compounds.

Aluminium chloride can be added in solid form or in solution inisobutyric acid chloride and chlorobenzene or 1,2-dichlorobenzene asdiluent.

The sequence of the addition of the reagents is important for thesuccess of the reaction. The best product qualities are obtained when1,1,3-trimethyl-3-phenylindan and isobutyric acid halide are firstbrought together and aluminium chloride is slowly metered in. The prioraddition of the acid chloride buffers the action of the aluminiumchloride and accordingly suppresses oligomer formation. In a variant,the aluminium chloride can be dissolved in the liquid acid halide andthen added dropwise to the aromatic compound.

In the isomeric mixture of compounds of formulae Ia and IIa, thecompound of formula Ia is the main component with a content of about60%.

The reaction temperature in step a) is from −20° C. to 20° C.,preferably from 0° C. to 10° C., especially from 0° C. to 5° C.

From 1.8 to 2.8 equivalents, preferably from 2.0 to 2.6 equivalents,especially from 2.2 to 2.4 equivalents, of isobutyric acid chloride,based on 1,1,3-trimethyl-3-phenylindan, are used.

The ketone of step (a) is obtained in the form of an isomeric mixtureand can be chlorinated in step (b) directly without being isolated.Chlorinating agents are sulfuryl chloride or chlorine gas. Thechlorination is preferably carried out by the introduction of chlorinegas at a temperature of from 20 to 90° C., preferably from 50 to 60° C.

Subsequent hydrolysis with aqueous alkali metal hydroxide (step c)yields a mixture of2-hydroxy-1-{3-[4-(2-hydroxy-2-methyl-proplonyl)phenyl]-1,1,3-trimethyl-indan--5-yl}-2-methyl-propan-1-oneand2-hydroxy-1-{1-[4-(2-hydroxy-2-methyl-propionyl)-phenyl]-1,3,3-trimethyl-indan-5-yl}-2-methyl-propan-1-onedissolved in the organic phase. In order to carry out the hydrolysismore rapidly it is advantageous to use a mixture of methanol and waterand subsequently acidify the reaction solution. The hydrolysis productis crystallised from a suitable solvent, for example toluene. Theconcentrated filtrates (mother liquors) also exhibft activity.

When chlorination and cooling of the reaction solution are complete(step b), the reaction solution begins to crystallise. Separation of theisomers can be carried out by recrystallisation, for example fromcyclohexane.

There is obtained isomerically pure2-chloro-1-(3-[4-(2-chloro-2-methyl-proplonyl)-phenyl]-1,1,3-trimethyl-indan-5-yl)-2-methyl-propan-1-one(formula Ib), which can be hydrolysed separately. After the hydrolysis,the crystalline compound of formula I is obtained.

The crystalline compound of formula II is prepared from the motherliquor by hydrolysis.

The invention accordingly relates also to a process for the preparationof a crystalline compound of formula I

which process comprises the following steps:

-   -   a) the slow addition of aluminium chloride, in portions, to a        solution comprising 1,1,3-trimethyl-3-phenylindan and isobutyric        acid halide in a suitable solvent at a reaction temperature of        from −20° C. to 20° C., an isomeric mixture consisting of        compounds of formulae Ia and IIa being obtained    -   b) enol chlorination of compounds Ia and IIa, an isomeric        mixture consisting of compounds of formulae Ib and IIb being        obtained    -   c) separation of the compound of formula Ib by recrystallisation    -   d) hydrolysis of compound Ib.

The invention relates also to a process for the preparation of acrystalline compound of formula II

which process comprises the following steps:

-   -   a) the slow addition of aluminium chloride, in portions, to a        solution comprising 1,1,3-trimethyl-3-phenylindan and isobutyric        acid halide in a suitable solvent at a reaction temperature of        from −20° C. to 20° C., an isomeric mixture consisting of        compounds of formulae Ia and IIa being obtained    -   b) enol chlorination of compounds Ia and IIa, an isomeric        mixture consisting of compounds of formulae Ib and IIb being        obtained    -   c) separation of the compound of formula Ib by recrystallisation    -   d) hydrolysis of compound IIb.

The crystalline isomeric mixture of (compounds of formulae I and II) andthe crystalline isomerically pure compounds are suitable asphotoinitiators. Preferred applications are in pigmented andnon-pigmented surface coatings, overprint coatings, powder coatings,printing inks, gel coats, composite materials or glass fibre coatings.Application in non-pigmented coatings is much more important than inpigmented coatings, because the product is subject to only a smallamount of yellowing.

The following Examples illustrate the novel preparation process indetail.

EXAMPLE 1

1.1) Friedel-Crafts reaction addition of AlCl₃ in solid form

153.6 g (0.65 mol) of 1,1,3-trimethyl-3-phenylindan (from SchenectadyPratteln Switzerland), 159.3 g (1.495 mol) of isobutyric acid chlorideand 195 g of 1,2-dichlorobenzene are placed in a 750 ml reaction flaskand cooled to 5-0° C. by means of an ice bath. In the course of abouttwo to three hours, 208.0 g (1.56 mol) of aluminium chloride are thenadded in small portions at an internal temperature of 5-20° C. HCl gasis evolved. Stirring is then carried out for about 16 hours at aninternal temperature of 0-5° C. At the end of that period, all thealuminium chloride has dissolved. The reddish reaction mixture is thenpoured onto ice and water and stirred to complete the reaction. The twophases are separated in a separating funnel. The organic phase is washedwith water and then concentrated for a short time in a vacuum rotaryevaporator at about 60° C. and about 25 mbar. There are obtained 413 gof yellowish oil, an isomeric mixture having1-[3-(4-isobutyryl-phenyl1,1,3-trimethyl-indan-5-yl]-2-methyl-propan-1-oneas the main component and1-[1-(4-isobutyrrl-phenyl)-1,3,3-trimethyl-indan-5-yl]-2-methyl-propan-1-oneas the subsidiary component dissolved in 1,2-dichlobenzene. Excludingthe solvent 1,2-dichlorobenzene, about 60% of the main component andabout 40% of the subsidiary component are found in the GC and ¹H-NMRspectrum. The isomeric mixture is used in the next reaction withoutbeing purified further.

1.2) Enol chlorination 413 g (0.65 mol tq) of the solution of theisomeric mixture from the Friedel-Crafts reaction having1-[3-(4-isobutyryl-phenyl)-1,1,3-trimethyl-indan-5yl]-2-methyl-propan-1-oneas the main component and1-[1-(4-isobutyryl-phenyl)-1,3,3-trimethyl-indan-5-yl]-2-methyl-propan-1-oneas the subsidiary component are placed in a 750 ml reaction flask andheated to 55-60° C. by means of an oil bath. Then, at 55-60° C., withthorough stirring, 92.2 g (1.30 mol) of chlorine gas are introducedthrough a glass frit, relatively quickly at the start and just slowly atthe end. HCl gas is evolved. The duration of the introduction is aboutfive to six hours. The reaction is monitored by means of the ¹H-NMRspectrum. Cooling is then carried out and the reaction solution beginsto crystallise. The slightly yellowish suspension is cooled to about 5°C. and filtered. The crystals are washed with 154 g of mixed hexanes anddried in vacuo. 160 g of white crystals are obtained. An 80 g sample isrecrystallised with three times the amount of cyclohexane. 66.3 g ofwhite crystals are obtained. According to the ¹H-NMR spectrum they areisomerically pure2-chloro-1-{3-[4-(2-chloro-2-methyl-proplonyl)-phenyl]-1,1,3-trimethyl-indan-5-yl}-2-methyl-propan-1-oneand they melt at 142.5-143.5° C.

Elemental analysis: (455.43) % C % H % d calculated: 70.11 calculated:6.79 calculated: 15.92 found: 70.05 found: 6.86 found: 16.00

The mother liquor, 317 g of yellowish solution with mixed hexanes and1,2-dichlorobenzene, is concentrated and distilled. 179 g tq ofyellowish solution remain. According to the ¹H-NMR spectrum thesubsidiary component2-chloro-1-(1-[4-(2-chloro-2-methyl-proplonyl)-phenyl]-1,3,3methyl-indan-5-yl)-2-methyl-propan-1-oneis enriched therein (about 81% to 19%). The 179 g of solution are usedin the next reaction without being purified further.

1.3) Hydrolysis of the subsidiary component2chloro-1-(1-[4-(2-chloro-2-methyl-propionyl)-phenyl]-1,3,3-trimethyl-indan-5-yl)-2-methyl-propan-1-onefrom the chlorination 93.3 g (0.70 mol) of 30% concentrated NaOH and 93ml of deionised water and 92 g of methanol are combined in a 750 mlreaction flask. There are then added dropwise at 50° C. in the course ofabout 30 minutes, with thorough stirring, 179 g (0.2908 mol tq) of asolution, in 1,2-dichlorobenzene, of the subsidiary component2chloro-1-(1-[4-(2-chloro-2-methyl-proplonyl)phenyl]-1,3,3-trimethyl-indan-5-yl)-2-methyl-propan-1-onefrom the preceding chlorination reaction, additionally diluted with 46 gof methanol. The internal temperature slowly rises to 55-60° C. Theorange alkaline mixture (about pH 12) is then stirred for about three tofour hours at 55-60° C. The conversion is checked with a GC sample and a¹H-NMR sample. The mixture is then cooled to 45° C. and adjusteddropwise to a pH of about 1-2 with about 37 g of 16% hydrochloric acid.The colour of the emulsion changes from yellow to pale yellow. Themixture is then stirred for about one hour at 60° C. When the hydrolysisis complete, the reaction mixture is neutralised with a small amount ofdilute sodium hydroxide solution. The two phases are separated at about25° C. in a separating funnel. The organic phase is concentrated in arotary evaporator. There are obtained 179.4 g of oil, which is subjectedto steam distillation in order to remove the 1,2-dichlorobenzene. At theend of the distillation, 114.2 g of yellow viscous oil are obtained.This corresponds to a tq yield of 96% of theory (408.54) over all threereaction steps. A 30 g sample is stirred with 30 g of diethyl ether andseeded. The crystals are filtered off, washed and dried. There areobtained 10 g of white crystals, which melt at 124.0-125.5° C. In the¹H-NMR spectrum, the isomerically pure subsidiary component2-hydroxy-1-(1-[4-(2-hydroxy-2-methyl-propionyl)-phenyl]-1,3,3-trimethyl-indan-5-yl)-2-methyl-propan-1-oneis found.

Elemental analysis: (408.54) % C % H calculated: 76.44 calculated: 7.90found: 76.31 found: 7.92

A sample of those crystals is again crystallised from toluene, and thewhite crystals then melt at 125.5-127.8° C.

Elemental analysis: (408.54). % C % H calculated: 76.44 calculated: 7.90found: 76.59 found: 7.84

1.4) Hydrolysis of the main component2-chloro-1-{3-[4-(2-chloro-2-methyl-proplonyl)-phenyl]-1,1,3-trimethyl-indan-5-yl}-2-methyl-propan-1-onefrom the chlorination 47.4 g (0.356 mol) of 30% concentrated NaOH and 47ml of deionised water and 47 g of methanol are combined in a 500 mlreaction flask. There are then added dropwise at 50° C. in the course ofabout 30 minutes, with thorough stirring, 66.0 g (0.1482 mol) ofrecrystallised main component2-chloro-1-{3-[4-(2-chloro-2-methyl-proplonyl)-phenyl]-1,1,3-trimethyl-indan-5-yl}-2-methyl-propan-1-onefrom the preceding chlorination reaction, dissolved in 190 g of tolueneand 23 g of methanol in the warm state. The internal temperature slowlyrises to 54° C. The alkaline emulsion (about pH 12) is then stirred at55-60° C. The conversion is checked with a GC sample and a ¹H-NMRsample. 60 g of methanol are then additionally added in two portions, inorder to accelerate the reaction. The duration of the hydrolysis isabout five to six hours. The mixture is then cooled to 35° C. andadjusted dropwise to a pH of about 1-2 with about 15 g of 16%hydrochloric acid. The colour of the emulsion lightens to pale yellow.The mixture is then stirred for about one hour at 60° C. When thehydrolysis is complete, the reaction mixture is neutralised with a smallamount of dilute sodium hydroxide solution. The two phases are separatedat about 25° C. in a separating funnel. The organic phase isconcentrated in a rotary evaporator. It crystallises spontaneously. Thecrystals are dried without being purified further. There are obtained60.2 g of white crystals, which melt at 116.5-118.5° C. This correspondsto a tq yield of 99% of theory (408.54) over the last reaction step anda tq yield of 82% of theory (408.54) over all three reaction steps. Inthe ¹H-NMR spectrum, the isomerically pure main component2-hydroxy-1-{3-[4-(2-hydroxy-2-methyl-propionyl)phenyl]-1,1,3-trimethyl-indan-5-yl}-2-methyl-propan-1-oneis found.

EXAMPLE 2

2.1) Friedel-Crafts reaction A portion of the AlCI₃ is added dropwise indissolved form 90 g (0.845 mol) of isobutyric acid chloride and 70 g of1,2-dichlorobenzene are placed in a 500 ml reaction flask and cooled to5-0° C. by means of an ice bath. In the course of about 20 minutes, 66.7g (0.50 mol) of aluminium chloride are then added in small portions atan internal temperature of 5-0° C. The dissolution prccess is slightlyexothermic. The yellowish solution is kept at an internal temperature of5-0° C.

100.0 g (0.423 mol) of 1,1,3-trimethyl-3-phenylindan (from SchenectadyPrattein Switzerland), 13.7 g (0.128 mol) of isobutyric acid chlorideand 100 g of 1,2-dichlorobenzene are placed in a 750 ml reaction flaskand cooled to 5-0° C. by means of an ice bath. The aluminium chloridesolution is then added dropwlse in the course of 90 minutes at aninternal temperature of 5-0° C. The solution becomes yellow and HCl gasis evolved. About 1% starting material is then found in the GC inaddition to the mono compound. A further 68.7 g (0.515 mol) of aluminiumchloride are then added in small portions in the course of one hour atan internal temperature of 5-0° C. HCl gas is further evolved. Thesuspension is then stirred for about 20 hours at an internal temperatureof 0-5° C. The reaction conversion is monitored by means of GC. At theend of that period, all the aluminium chloride has dissolved. The redreaction mixture is then poured onto ice and water and stirred tocomplete the reaction. The two phases are separated in a separatingfunnel. The organic phase is washed with water and then concentrated fora short time in a vacuum rotary evaporator at about 60° C. and about 25mbar. There are obtained 357.8 g of a reddish liquid, an isomericmixture having1-[3-(4-isobutyryl-phenyly-1,1,3-trimethyl-indany-5-yl]-2-methyl-propan-1-oneas the main component and1-[3-(4-isobutyryl-phenyl)-1,3,3-trimethyl-indan-5-yl]-2-methyl-propan-1-oneas the subsidiary component, dissolved in 1,2-dichlorobenzene. Excludingthe solvent 1,2-dichlorobenzene, about 60% of the main component andabout 40% of the subsidiary component are found in the GC and ¹H-NMRspectrum. The isomeric mixture is used in the next reaction withoutbeing purified further.

2.2) Enol chlorination 322.0 g (0.3807 mol tq) of the solution of theisomeric mixture from the Friedel-Crafts reaction having1-[3-(4-isobutyryl-phenyl)-1,1,3-trimethyl-indan-5-yl]-2-methyl-propan-1-oneas the main component and1-[1-(4-isobutyryl-phenyl)-1,3,3-trimethyl-indan-5-yl]-2-methyl-propan-1-oneas the subsidiary component are placed in a 750 ml reaction flask andheated to 55-60° C. by means of an oil bath. Then, at 55-60° C., withthorough stirring, 56.0 g (0.79 mol) of chlorine gas are introducedthrough a glass frit, relatively quickly at the start and just slowly atthe end. HCl gas is evolved. The duration of the introduction is aboutsix to seven hours. The reaction is monitored by means of the ¹H-NMRspectrum. Cooling is then carried out and the reaction solution beginsto crystallise. The white suspension is cooled to about 5° C. andfiltered. The crystals are washed with 110 g of mixed hexanes and, whilestill moist (about 81 g), are recrystallised from 260 g of cyclohexane,filtered, washed and dried. 68.7 g of white crystals are obtained. Thiscorresponds to a partial yield of 40.5% of theory (445.43) over tworeaction steps. According to the ¹H-NMR spectrum they are isomericallypure2-chloro-1-(3-[4-(2-chloro-2-methyl-propionyl)-phenyl]-1,1,3-trimethyl-indan-5-yl)-2-methyl-propan-1-oneand they melt at 142.5-143.7° C.

The mother liquors are collected and concentrated in vacuo. Water isadded to the residue, 277.5 g of yellowish oil, and 1,2-dichlorobenzeneis removed by steam distillation. The viscous yellowish residue Isdissolved at about 60° C. in 125 g of mixed hexanes, cooled and seeded.The crystals are filtered off, washed with mixed hexanes and dried.There are obtained 22.7 g of pale beige crystals, which melt at 110-119°C. According to the ¹H-NMR spectrum they are no longer isomericallypure. The mother liquor is concentrated and yields 83.5 g tq of yellowoil. According to the ¹H-NMR spectrum the subsidiary component2-chloro-1-(1-[4-(2-chloro-2-methyl-propionyl)-phenyl]-1,3,3-trimethyl-indan-5-yl)-2-methyl-propan-1-oneis enriched therein (about 83% to 17%). The 83.5 g of yellow oil areused in the next reaction without being purified further.

The 22.7 g of crystals are recrystallised from 88 g of cydohexane,flitered and dried. There are obtained 9.0 g of white crystals, whichmelt at 135-140° C. According to the ¹H-NMR spectrum they are a mixtureof 91% of the main component2-chloro-1-{3-[4-(2-chloro-2-methyl-proplonyl)-phenyl]-1,1,3-trimethyl-indan-5yl}-2-methyl-propan-1-oneand 9% of the subsidiary component2-chloro-1-{1-[4-(2-chloro-2-methyl-propionyl)-phenyl]-1,3,3-trimethyl-indan-5-yl}-2-methyl-propan-1-one.In the concentrated mother liquor, 12.0 g of a yellow viscous oil, thesubsidiary component2-chloro-1-(1-[4-(2-chloro-2-methyl-proplonyl)-phenyl]-1,3,3-trimethyl-indan-5-yl)-2-methyl-propan-1-oneis enriched (about 67% to 33%).

2.3) Hydrolysis of the subsidiary component2-chloro-1-(1-[4-(2-cloro-2-methyl-proplonyl)-phenyl]-1,3,3-trimethyl-indan-5-yl)-2-methyl-propan-1-onefrom the chlorination 56.0 g (0.42 mol) of 30% concentrated NaOH and 56ml of deionised water and 55 g of methanol are combined in a 750 mlreaction flask. There are then added dropwise at 55° C. in the course ofabout 30 minutes, with thorough stirring, 83.0 g (0.1745 mol tq) of oilof the subsidiary component2-chloro-1-{1-[4-(2-chloro-2-methyl-propionyl)-phenyl]-1,3,3-trimethyl-indan-5-yl}-2-methyl-propan-1-onefrom the preceding chlorination reaction, additionally diluted with 200g of toluene and with 29 g of methanol. The internal temperature remainsat 55-60° C. The yellowish-orange alkaline emulsion (about pH 11) isthen stirred for about five to six hours at 55-60° C. The conversion ischecked with a GC sample and a ¹H-NMR sample. The mixture is then cooledto 40° C. and adjusted dropwise to a pH of about 1-2 with about 25 g of16% hydrochloric acid. The colour of the emulsion changes from yellow topale yellow. The mixture is then stirred for about one hour at 60° C.When the hydrolysis is complete, the reaction mixture is neutralisedwith a small amount of dilute sodium hydroxide solution. The two phasesare separated at about 25° C. in a separating funnel. The organic phaseis concentrated in a vacuum rotary evaporator. There are obtained 77.7 gof oil. 100 g of diethyl ether are added to the oil, followed by heatingand seeding with crystals. A portion crystallises out overnight. Thesuspension is cooled to about 0° C. and filtered. The crystals arewashed with 30 g of diethyl ether and dried. There are obtained 15.7 gof white crystals, which melt at 122.0-124.5° C. In the ¹HMR spectrum,the isomerically pure subsidiary component2-hydroxy-1-(1-[4-(2-hydroxy-2-methyl-proplonyl)-phenyl]-1,3,3-trimethyl-indan-5-yl2-methyl-propan-1-oneis found. The mother liquor is concentrated and there are obtained 58 gof yellowish oil which, according to the ¹H-NMR spectrum, is an isomericmixture.

2.4) Hydrolysis of the main component2-chloro-1-{3-[4-(2-chloro-2-methyl-proplonyl)-phenyl]-1,1,3-trimethyl-inan-5-yl}-2-methyl-propan-1-one from the chlorination 48.0 g (0.36 mol) of 30% concentrated NaOHand 48 ml of deionised water and 48 g of methanol are combined in a 500ml reaction flask. There are then added dropwise at 50° C. in the courseof about 45 minutes, with thorough stirring, 66.8 g (0.150 mol) of therecrystallised main component,2-chloro-1-(3-[4-(2-chloro-2-methyl-propionyl)-phenyl]-1,1,3-trimethyl-indan-5-yl)-2-methyl-propan-1-one,from the preceding chlorination reaction, dissolved in 190 g of tolueneand 83 g of methanol in the warm state. The internal temperature slowlyrises to 56° C. The alkaline emulsion (about pH 11) is then stirred at55-60° C. The conversion is checked with a GC sample and a ¹H-NMRsample. The duration of the hydrolysis is about four to five hours. Themixture is then cooled to 35° C. and adjusted dropwlse to a pH of about1-2 with about 16.4 g of 16% hydrochloric acid. The colour of theemulsion lightens. The mixture is then stirred for about one hour at 60°C. When the hydrolysis is complete, the reaction mixture is neutralisedwith a small amount of dilute sodium hydroxide solution. The two phasesare separated at about 40° C. in a separating funnel. The organic phaseis concentrated in a rotary evaporator. There are obtained 65.0 g ofcolourless viscous oil, which slowly crystallises. The crystals arerecrystallised from 100 g of toluene and dried. There are obtained 54.9g of white crystals, which melt at 117.7-119.0° C. This corresponds to atq yield of 90% of theory (408.54) over the last reaction step. In the¹H-NMR spectrum, the isomerically pure main component2-hydroxy-1-(3-[4-(2-hydroxy-2-methyl-propionyl)-phenyl]-1,1,3-trimethyl-indan-5-yl)-2-methyl-propan-1-oneis found.

Elemental analysis: (408.54) % C % H calculated: 76.44 calculated: 7.90found: 76.26 found: 7.88

A sample of those crystals is again crystallised from toluene, and thewhite crystals then melt at 117.8-119.0° C. Concentration of the motherliquor yields a further 6.1 g of colourless highly viscous oil.According to the ¹H-HMR spectrum, there are about 75% of the maincomponent and about 25% of the subsidiary component therein.

Elemental analysis: (408.54) % C % H calculated: 76.44 calculated: 7.90found: 76.32 found: 7.84

EXAMPLE 3

3.1) Friedel-Crafts reaction Addition of AlCl₃ in solid form 153.6 g(0.65 mol) of 1,1,3-trimethyl-3-phenylindan (from Schenectady PratteinSwitzerland), 159.3 g (1.495 mol) of isobutyric acid chloride and 203 gof 1,2-dichlorobenzene are placed in a 750 ml reaction flask and cooledto 5-0° C. by means of an ice bath. In the course of about two to threehours, 208.0 g (1.56 mol) of aluminium chloride are then added in smallportions at an internal temperature of 5-0° C. HCl gas is evolved.Stirring is then carried out for about 17 hours at an internaltemperature of 0-5° C. At the end of that period, all the aluminiumchloride has dissolved. The reddish reaction mixture is then poured ontoice and water and stirred to complete the reaction. The two phases areseparated in a separating funnel. The organic phase is washed with waterand then concentrated for a short time in a vacuum rotary evaporator atabout 60° C. and about 25 mbar. There are obtained 572 g of reddish oil,an isomeric mixture having1-[3-(4-isobutyryl-phenyl)-1,1,3-trimethyl-indan-5-yl]-2-methyl-propan-1-oneas the main component and1-[1-(4-isobutyryl-phenyl)-1,3,3-trimethyl-indan-5-yl]-2-methyl-propan-1-oneas the subsidiary component, dissolved in 1,2-dichloro-benzene.Excluding the solvent 1,2-dichlorobenzene, about 60% of the maincomponent and about 40% of the subsidiary component are found in the GCand ¹H-NMR spectrum. The isomeric mixture is used in the next reactionwithout being purified further.

3.2) Enol chlorination 572 g (0.65 mol tq) of the solution of theisomeric mixture from the Friedel-Crafts reaction having1-[3-(4-isobutyryl-phenyl)1,1,3-trimethyl-indan-5-yl]-2-methyl-propan-1-oneas the main component and1-[1-(4-isobutyryl-phenyl)-1,3,3-trimethyl-indan-5-yl]-2-methyl-propan-1-oneas the subsidiary component are placed in a 750 ml reaction flask andheated to 55-60° C. by means of an oil bath. Then, at 55-60° C., withthorough stirring, 92.2 g (1.30 mol) of chlorine gas are introducedthrough a glass frit, relatively quickly at the beginning and justslowly at the end. HCl gas is evolved. The duration of the introductionis about four to five hours. The reaction is monitored by means of the¹H-NMR spectrum. The reaction solution is then heated to about 108° C.in order to remove the HCl gas. 150 g of water are then added and the1,2-dichlorobenzene is removed by steam distillation. About 195 g of1,2-dichloro-benzene are recovered. 250 g of toluene are added to thehot oil, and the water is then separated off. The yellow isomericmixture consisting of2-chloro-1-(3-[4-(2-chloro-2-methyl-proplonyl)-phenyl]-1,1,3-trimethyl-indan-5-yl)-2-methyl-propan-1-oneas the main component and2-chloro-1-(1-[4-(2-chloro-2-methyl-propionyl)-phenyl]-1,3,3-trimethyl-indan-5-yl)-2-methyl-propan-1-oneas the subsidiary component is used in the next reaction without beingpurified further.

3.3) Hydrolysis of the isomeric mixture from the chlorination,consisting of2-chloro-1-(3-[4-(2-chloro-2-methyl-propionyl)-phenyl]-1,1,3-trimethyl-indan-5-yl)-2-methyl-propan-1-oneas the main component and2-chloro-1-(1-[4-(2-chloro-2-methyl-propionyl)-phenyl]-1,3,3-trimethyl-indan-5-yl)-2-methyl-propan-1-oneas the subsidiary component

208 g (0.156 mol) of 30% concentrated NaOH and 208 ml of delonised waterand 206 g of methanol are combined in a 1.5 litre reaction flask andheated. There are then added drop-wise at 50° C. in the course of about30 minutes, with thorough stirring, a total of about 650 ml (0.65 moltq) of a solution, in toluene, of the isomeric mixture from thepreceding chlorination, consisting of2-chloro-1-(3-[4-(2-chloro-2-methyl-propionyl)-phenyl]-1,1,3-trimethyl-indan-5-yl)-2-methyl-propan-1-oneas the main component and2-chloro-1-{1-[4-(2-chloro-2-methyl-propionyl)-phenyl]-1,3,3-trimethyl-indan-5-yl}-2-methyl-propan-1-oneas the subsidiary component, additionally diluted with 103 g ofmethanol. The internal temperature slowly rises to 55-60° C. The orangealkaline mixture (about pH 12) is then stirred for about three to fourhours at 55-60° C. The conversion is checked with a GC sample and a¹H-MR sample. The mixture is then heated to 70° C. and stirred for afurther five hours. The conversion is again checked with a GC sample anda ¹H-NMR sample. The mixture is then cooled to 45° C. and slowlyadjusted to a pH of about 1-2 with about 152 g of 16% hydrochloric acid.The temperature rises by about 7° C. The colour of the emulsion changesfrom golden yellow to pale yellow. The mixture is then stirred for aboutone hour at 55-60° C. When the hydrolysis is complete, the reactionmixture is neutralised with a small amount of dilute sodium hydroxidesolution. The two phases are separated at about 25° C. in a separatingfunnel. The organic phase is washed with 200 ml of brine and separatedoff again. There is no spontaneous crystallisason at room temperature.The organic phase is concentrated in a rotary evaporator. 208.8 g ofyellowish oil are obtained and checked with a ¹H-NMR sample (Example3.3a)

Elemental analysis: (408.54) % C % H calculated: 76.44 calculated: 7.90found: 76.23 found: 7.97

70 g of toluene are added to 140.4 g of oil, which is dissolved at 50°C. and cooled. After seeding with crystals, crystallisation slowlybegins. The suspension is cooled to 5° C. The crystals are then filteredoff, washed twice with 30 g of cold toluene and dried in vacuo. Thereare obtained 72.4 g of white crystals, which melt at 97-105° C. Thiscorresponds to a tq yield of crystals of 54.5% of theory (408.54) overall three reaction steps. In the ¹H-NMR spectrum there is found anisomeric ratio of about 60% of the main component2-hydroxy-1-{3-[4-2-hydroxy-2-methyl-propionyl)-phenyl]-1,1,3-trimethyl-indan-5-yl}-2-methyl-propan-1-oneand about 40% of the subsidiary component2-hydroxy-1-(1-[4-(2-hydroxy-2-methyl-propionyl)-phenyl]-1,3,3-trimethyl-indan-5-yl)-2-methyl-propan-1-one.The filtrate is concentrated, and 57.2 g of viscous yellow oil areobtained. This corresponds to a tq yield of oil of 43.1% of theory(408.54) over all three reaction steps. The overall yield of crystalsand oil is 97.6% of theory (408.54) over all three reaction steps.

EXAMPLE 4

4.1) Friedel-Crafts reaction Addition of AlCl₃ in solid form 153.6 g(0.65 mol) of 1,1,3-trimethyl-3-phenylindan (from Schenectady PratteinSwitzerland), 159.3 g (1.495 mol) of isobutyric acid chloride and 203 gof 1,2-dichlorobenzene are placed in a 750 ml reaction flask and cooledto 5-0° C. by means of an Ice bath. In the course of about two to threehours, 208.0 g (1.56 mol) of aluminium chloride are then added in smallportions at an internal temperature of 5-0° C. HCl gas is evolved.Stirring is then carried out for about 16 hours at an internaltemperature of 0-5° C. At the end of that period, all the aluminiumchloride has dissolved. The reddish-yellow reaction mixture is thenpoured onto ice and water and stirred to complete the reaction. The twophases are separated in a separating funnel. The organic phase is washedwith water and then concentrated for a short time in a vacuum rotaryevaporator at about 60° C. and about 25 mbar. There are obtained 510.5 gof yellowish oil, an isomeric mixture having1-[3-(4-isobutyryl-phenyl)-1,1,3-trimethyl-indan-5-yl]-2-methyl-propan-1-oneas the main component and1-[1-4-isobutyryl-phenyl)-1,3,3-trimethyl-indan-5-yl]-2-methyl-propan-1-oneas the subsidiary component dissolved in 1,2-dichlorobenzene. Excludingthe solvent 1,2-dichlorobenzene, about 60% of the main component andabout 40% of the subsidiary component are found in the GC and ¹H-NMRspectrum. The isomeric mixture is used in the next reaction withoutbeing purified further.

4.2) Enol chlorination 510 g (0.65 mol tq) solution of the isomericmixture from the Friedel-Crafts reaction having1-[3-(4-isobutyryl-phenyl)-1,1,3-trimethyl-indan-5-yl]-2-methyl-propan-1-oneas the main component and1-[1-(4-isobutyryl-phenyl)-1,3,3-trimethyl-indan-5-yl]-2-methyl-propan-1-oneas the subsidiary component are placed in a 750 ml reaction flask andheated to 60-65° C. by means of an oil bath. Then, at 60-65° C., withthorough stirring, 94.3 g (1.33 mol) of chlorine gas are introducedthrough a glass frit, relatively quickly at the beginning and justslowly at the end. HCl gas is evolved. The duration of the introductionis about four to five hours. The reaction is monitored by means of the¹H-NMR spectrum. The colourless reaction solution is then heated toabout 100° C. in order to remove the HCl gas. 100 g of water are thenadded and the 1,2-dichlorobenzene is removed by steam distillation.About 195 g of 1,2-dichloro-benzene are recovered. 250 g of toluene areadded to the hot oil, and the water is then separated off. The isomericmixture consisting of2-chloro-1-(3-[4-(2-chloro-2-methyl-propionyl)-phenyl]-1,1,3-trimethyl-indan-5-yl)-2-methyl-propan-1-oneas the main component and2-chloro-1-(1-[4-(2-chloro-2-methyl-proplonyl)-phenyl]-1,3,3-trimethyl-indan-5-yl-2-methyl-propan-1-oneas the subsidiary component is used in the next reaction without beingpurified further.

4.3) Hydrolysis of the isomeric mixture from the chlorination,consisting of2-chloro-1-(3-[4-(2-chloro-2-methyl-propionyl)-phenyl]-1,1,3-trimethyl-indan-5-yl)-2-methyl-propan-1-oneas the main component and2-chloro-1-{1-[4-(2-chloro-2-methyl-propionyl)-phenyl]-1,3,3-trimethyl-indan-5-yl}-2-methyl-propan-1-oneas the subsidiary component 208 g (0.156 mol) of 30% concentrated NaOHand 208 ml of delonised water and 206 g of methanol are combined in a1.5 litre reaction flask and heated. There are then added drop-wise at50° C. in the course of about 30 minutes, with thorough stirring, atotal of about 650 ml (0.65 mol tq) of a solution, in toluene, of theisomeric mixture from the preeeding chlorination consisting of2-chloro-1-{3-[4-(2-chloro-2-methyl-propionyl)-phenyl]-1,1,3-trimethyl-indan-5-yl}-2-methyl-propan-1-oneas the main component and2-chloro-1-(1-[4-(2-chloro-2-methyl-proplonyl)-phenyl]-1,3,3-trimethyl-indan-5-yl)-2-methyl-propan-1-oneas the subsidiary component, additionally diluted with 103 g ofmethanol. The internal temperature slowly rises to 55-60° C. The orangealkaline mixture (about pH 12) is then stirred for about six to sevenhours at 65-70° C. The conversion is checked with a GC sample and a¹H-NMR sample. The yellow mixture is then cooled to 30° C. and slowlyadjusted to a pH of about 1-2 with about 89.4 g of 16% hydrochloricacid. The temperature rises by about 7° C. The colour of the emulsionchanges from yellow to pale yellow. The mixture is then stirred forabout one hour at 55-60°C. When the hydrolysis is complete, the reactionmixture is neutralised with a small amount of dilute sodium hydroxidesolution. The two phases are separated at about 35° C. in a separatingfunnel. The organic phase is washed with 200 ml of brine and separatedoff again. There is no spontaneous crystallisation at room temperature.The organic phase is concentrated in a rotary evaporator. 332 g ofyellowish oil are obtained and checked with a ¹H-NMR sample.

65 g of toluene are added to the 332 g of oil, which is dissolved at 40°C. and stirred. After seeding with 0.1 g of crystals, crystallisationslowly begins. On the following day, the slightly yellowish suspensionis cooled to 10° C. The crystals are then filtered off, washed twicewith 30 g of cold toluene and dried in vacuo. There are obtained 176.8 gof white crystals, which melt at 93-103° C. This corresponds to a tqyield of crystals of 66.6 % of theory (408.54) over all three reactionsteps. The filtrate is concentrated, and 63.4 g of viscous yellowish oilare obtained. (Example 4.3 b) This corresponds to a tq yield of oil of23.9% of theory (408.54) over all three reaction steps. The overallyield of crystals and oil is 90.5% of theory (408.54) over all threereaction steps.

The 176.8 g of white crystals are again dissolved at 80° C. in 90 g oftoluene, cooled and seeded at room temperature. Crystalliation slowlybegins. After 48 hours' stirring, the thick mass is diluted with 45 g oftoluene and then filtered. The crystals are washed with 120 g of tolueneand dried in vacuo at about 50° C. There are obtained 138.8 g of whitecrystals, which melt at 101.5-107° C. The filtrate is concentrated and37.6 g of viscous yellowish oil are obtained. (Example 4.3 c) in the¹H-NMR spectrum of the crystals and of the oil there is found anisomeric ratio of about 60% of the main component2-hydmoxy-1-(3-[4-(2-hydroxy-2-methyl-propionyl)-phenyl]-1,1,3-trimethyl-indan-5-yl)-2-methyl-propan-1-oneand about 40% of the subsidiary component2-hydroxy-1-(1-[4-(2-hydroxy-2-methyl-propionyl)-phenyl]-1,3,3-trimethyl-indan-5-yl)-2-methyl-propan-1-one.(Example 4.3 d)

Elemental analysis of the crystals: (408.54) % C % H calculated: 76.44calculated: 7.90 found: 76.42 found: 7.96

APPLICATION EXAMPLES Example A1 UV-Curable Overprint Coating

The 1-phenylindans according to the invention were tested for theirsuitability as photoinitiators in a UV-curable overprint coating (OPV)and compared with a commercially available product (Esacure KIP 150,Lamberti). The composition of the OPV is shown in the table below.Component % by weight Ebecryl 605 35.0 Ebecryl 40 10.0 OTA 480 30.0TPGDA 24.0 Ebecryl 1360 0.5 Dow Corning 57 0.5 Σ 100.0OTA 480: glycerol propoxylate triacrylate (UCB)TPGDA: tripropylene glycol diacrytate (UCB)Ebecryl 605: bisphenol A epoxyacrylate, diluted with 25% TPGDA (UCB)Ebecryl 40: pentaerythritol ethoxylate tetraacrylate (UCB)Ebecryl 1360: hexafunctional silicone acrylate (UCB)Dow Corning 57: silicone additive, flow improver (Dow Corning)

0.6 g and 0.8 g of each photoinitiator was weighed in per 10 g offormulation. The samples were applied by means of a knife to white cardin a layer thickness of 6 μm and then exposed by means of a UV exposuredevice (IST) under two medium-pressure mercury lamps each of 120 W/cm.Immediately after the exposure, the resistance of the coating surface towiping was determined by means of a paper towel. The curing speed is themaximum conveyor belt speed, in m/min, of the exposure device at whichthe coating surface remains resistant to wiping.

The yellowing of the overprint coatings (b* values) was determined 15minutes after the exposure as well as after an additional UV exposure(TLK 40/05 fluorescent tube) over a period of 22 hours. For thatpurpose, the samples were applied by means of a knife to white-coatedchipboard in a layer thickness of 100 μm and cured at a conveyor beltspeed of 10 m/min. A CM-508 i spectrophotometer (Minolta) was used formeasuring the b* values. The results obtained are shown in the followingtable. Photoinitiator Curing speed [m/min] Yellowing¹ Example 6%initiator 8% initiator b* (0)² b* (22)³ Esacure KIP 150 30 60 6.4 5.7Example 1.4 30 60 5.5 5.2 Example 1.3 30 70 5.0 4.7 Example 3.3a 25 605.5 6.9 Example 4.3b 25 50 6.2 8.4 Example 4.3c 30 50 6.1 8.0 Example4.3d 40 70 5.9 4.9¹Determined for an initiator concentration of 6%.²Measured 15 minutes after the exposure.³Measured after 22 hours' additional UV exposure (TLK 40/05 fluorescenttube).

In the tested UV -curable overprint coating, the same curingeffectiveness is observed for the 1-phenylindans according to theinvention of Examples 1.3 and 1.4 as for the commercial photoinitiatorEsacure KIP 150. With regard to yellowing, the compounds of Examples 1.3and 1.4 and 4.3d tend to result in lower values than Esacure KIP 150.

Example A2 Epoxy Acrylate Clear Coat

Formulation:

89.0% by weight Ebecryl 604 (75% epoxy acrylate in hexanedioldiacrylate, UCB)

10.0% by weight Sartomer SR 344 (polyethylene glycol 400 diacylate, CrayValley)

1.0% by weight Ebecryl 350 (silicone diacrylate, UCB)

The coatings were applied with a 6 μm (spiral coater No.1 yellow) coaterto aluminum sheets. They were cured with two 80 W/cm medium pressuremercury lamps at the maximum curing speed which is possible to obtain athrough-cure and tack-free surface. The results are shown in the Tablebelow (curing speed m/min).

The coatings were applied to chipboard (100 μm) and cured at a beltspeed of 10 m/min to determine the pendulum hardness, b* value(yellowing) and gloss after an exposure time of 30 minutes at ambienttemperature. The photoinitiator concentration is 2%. PhotoinitiatorCuring Speed Pendulum DE* Db* 2% (m/min) hardness (s) gloss yellowingESACURE KIP 150 45 192 3.3 3.1 Example 1.4 45 192 3.1 2.9 Example 1.3 35196 3.0 2.8 Example 3.3a 40 192 3.0 2.8 Example 4.3b 35 192 3.4 3.3Example 4.3c 35 193 3.4 3.3 Example 4.3d 50 189 3.1 3.0

1. A process for the preparation of a crystalline isomeric mixture ofcompounds of formulae I and II

which process comprises the following steps: a) the slow addition ofaluminium chloride, in portions, to a solution comprising1,1,3-trimethyl-3-phenylindan and isobutyric acid halide in a suitablesolvent at a reaction temperature of from −20° C. to 20° C., an isomericmixture consisting of compounds of formulae Ia and IIa being obtained

b) enol chlorination of compounds Ia and IIa, an isomeric mixtureconsisting of compounds of formulae Ib and IIb being obtained

c) hydrolysis of the chlorinated isomeric mixture from step b).
 2. Aprocess for the preparation of a crystalline compound of formula I

which process comprises a) the slow addition of aluminium chloride, inportions, to a solution comprising 1,1,3-trimethyl-3-phenylindan andisobutyric acid halide in a suitable solvent at a reaction temperatureof from −20° C. to 20° C., an isomeric mixture consisting of compoundsof formulae Ia and IIa being obtained

b) enol chlorination of compounds Ia and IIa, an isomeric mixtureconsisting of compounds of formulae Ib and IIb being obtained

c) separation of the compound of formula Ib by recrystallisation and d)hydrolysis of compound Ib.
 3. A process for the preparation of acrystalline compound of formula II

which process comprises a) the slow addition of aluminium chloride, inportions, to a solution comprising 1,1,3-trimethyl-3-phenylindan andisobutyric acid halide in a suitable solvent at a reaction temperatureof from −20° C. to 20° C., an isomeric mixture consisting of compoundsof formulae Ia and IIa being obtained

b) enol chlorination of compounds Ia and IIa, an isomeric mixtureconsisting of compounds of formulae Ib and IIb being obtained

c) separation of the compound of formula Ib by recrystallisation and d)hydrolysis of compound IIb.
 4. A process according to claim 1, whereinthe solvent is 1,2-dichlorobenzene and the reaction temperature of stepa) is from 0° C. to 5° C.
 5. A process according to claim 1, whereinpure 1,1,3-trimethyl-3-phenylindan and isobutyric acid halide are firstbrought together and aluminium chloride is metered in slowly in thecourse of from 2 to 3 hours, so that a local overdosing of aluminiumchloride is avoided.
 6. A process according to claim 2, wherein thesolvent is 1,2-dichlorobenzene and the reaction temperature of step a)is from 0° C. to 5° C.
 7. A process according to claim 3, wherein thesolvent is 1,2-dichlorobenzene and the reaction temperature of step a)is from 0° C. to 5° C.
 8. A process according to claim 2, wherein pure1,1,3-trimethyl-3-phenylindan and isobutyric acid halide are firstbrought together and aluminium chloride is metered in slowly in thecourse of from 2 to 3 hours, so that a local overdosing of aluminiumchloride is avoided.
 9. A process according to claim 3, wherein pure1,1,3-trimethyl-3-phenylindan and isobutyric acid halide are firstbrought together and aluminium chloride is metered in slowly in thecourse of from 2 to 3 hours, so that a local overdosing of aluminiumchloride is avoided.
 10. A process according to claim 4, wherein pure1,1,3-trimethyl-3-phenylindan and isobutyric acid halide are firstbrought together and aluminium chloride is metered in slowly in thecourse of from 2 to 3 hours, so that a local overdosing of aluminiumchloride is avoided.
 11. A process according to claim 5, wherein pure1,1,3-trimethyl-3-phenylindan and isobutyric acid halide are firstbrought together and aluminium chloride is metered in slowly in thecourse of from 2 to 3 hours, so that a local overdosing of aluminiumchloride is avoided.
 12. A process according to claim 6, wherein pure1,1,3-trimethyl-3-phenylindan and isobutyric acid halide are firstbrought together and aluminium chloride is metered in slowly in thecourse of from 2 to 3 hours, so that a local overdosing of aluminiumchloride is avoided.
 13. A process according to claim 7, wherein pure1,1,3-trimethyl-3-phenylindan and isobutyric acid halide are firstbrought together and aluminium chloride is metered in slowly in thecourse of from 2 to 3 hours, so that a local overdosing of aluminiumchloride is avoided.